A retarding potential type energy analyzer is a detector which selectively detects charged particles (e.g. electrons or ions) having amounts of energy equal to or higher than a specific level from the charged particles emitted from a charged-particle source (such as a sample being analyzed or charged-particle radiation source). A retarding potential type energy analyzer normally includes: three plate-shaped grid electrodes (front grid electrode, intermediate grid electrode and rear grid electrode) arranged at regular intervals in the travelling direction of the charged particles; a voltage applier for applying voltages to those grid electrodes; and a detector. As the grid electrodes, a plate-shaped electrode having a large number of through-holes bored in its thickness direction has been used (for example, Patent Literature 1). A mesh-like electrode consisting of woven wire has also been used.
In the retarding potential type energy analyzer, for example, the front and rear grid electrodes are grounded, while the intermediate grid electrode is supplied with a predetermined amount of voltage having the same polarity as the charged particles as the measurement target. As a result, a potential difference which blocks the entry of the charged particles is formed between the front and intermediate grid electrodes, while a potential difference which accelerates the charged particles toward the detector is formed between the intermediate and rear grid electrodes. The charged particles emitted from the sample are decelerated during their travel from the front grid electrode toward the intermediate grid electrode. Only the particles which have arrived at and passed through the intermediate grid electrode are guided to the detector.